Q.How Long Do I Wait Before I Can Use Seeds Taken From Peppers?
Store bought pepper seeds have not done anything in the seed starter mix. Some were old seeds and some were taken fresh from store bought peppers. No germination on any.

Certified GKH Gardening Expert
They will germinate fresh (after about a week of thorough drying), or after several years of storage. Usually, a lack of germination is due to overly wet starter mix. or taking from a green pepper that was not fully ripe. Peppers will enjoy alternating wet and dry conditions to germinate. This can take several weeks. Peppers that come from under ripe fruit will not germinate, at all.
https://www.gardeningknowhow.com/edible/vegetables/pepper/harvesting-pepper-seeds.htm
https://www.gardeningknowhow.com/edible/vegetables/pepper/store-bought-pepper-seeds.htm